Vol. 45, 1959 



BIOCHEMISTRY: KORNBERG ET AL. 



775 



undetectable (<0.5 per cent of the maximal value after infection with T2) in normal 

 cells or in extracts of cells infected with T5 (Fig. 2 A), a, phage without HMC in 

 its DNA. The maximal level of phosphorylating ("kinase") activity for dHMC-5- 

 P was of the same order as that of the kinases for the other deoxynucleotides in- 



1 



10 20 30 40 



5 I 10 20 30 40 

 Tl ME-minutes 



10 20 30 40 



Fig. 2. — Deoxynucleotide-phosphorylating enzymes ("kinases") and hydroxymethylating 

 enzyme levels before and after infection with phage T2 or T5. The arrow indicates the start 

 of infection ("zero minutes," see Method I). Assays were as referred to in Methods. 



128 



